ardupilot/APMrover2/balance_bot.cpp

#include<stdio.h>
#include "Rover.h"

// Function to set a desired pitch angle according to throttle
void Rover::balancebot_pitch_control(float &throttle)
{
    // calculate desired pitch angle
    const float demanded_pitch = radians(-throttle * 0.01f * g2.bal_pitch_max);

    // calculate speed from wheel encoders
    float veh_speed_pct = 0.0f;
    if (g2.wheel_encoder.enabled(0) && g2.wheel_encoder.enabled(1) && is_positive(g2.wheel_rate_control.get_rate_max_rads())) {
        veh_speed_pct = (g2.wheel_encoder.get_rate(0) + g2.wheel_encoder.get_rate(1)) / (2.0f * g2.wheel_rate_control.get_rate_max_rads()) * 100.0f;
        veh_speed_pct = constrain_float(veh_speed_pct, -100.0f, 100.0f);
    }

    // calculate required throttle using PID controller
    throttle = g2.attitude_control.get_throttle_out_from_pitch(demanded_pitch, veh_speed_pct, g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, G_Dt) * 100.0f;
}

// returns true if vehicle is a balance bot
// called in AP_MotorsUGV::output()
// this affects whether the vehicle tries to control its pitch with throttle output
bool Rover::is_balancebot() const
{
    return ((enum frame_class)g2.frame_class.get() == FRAME_BALANCEBOT);
}